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use types::Endianness;
use utils;
use structure::{Field,Structure};
use std::collections::HashMap;
// use fxhash::FxHashMap as HashMap;
use std::str;
use file_block::FileBlock;
use file::Header;
use types::{Error,Result};

fn sdna_string_list_and_next_pos(data: &[u8], endianness: Endianness) -> (Vec<String>, usize){
    let num_strings = utils::read_i32(data, endianness) as usize;
    let str_iter =  utils::ByteStringIter::new(&data[4..], num_strings);
    let mut next_pos = 0;
    let strings = str_iter.map(|(name, pos)|{
        next_pos = pos;
        name.to_string()
    }).collect();
    (strings, next_pos + 4)
}


fn sdna_u16_list_with_size(data: &[u8], num_elements: usize, endianness: Endianness) -> Vec<u16>{
    data.chunks(2).take(num_elements).map(|two_bytes| utils::read_u16(two_bytes, endianness)).collect()
}

#[derive(Clone)]
pub struct SDNA{
    block: FileBlock,
    endianness: Endianness,
    pointer_bytes: usize,
    names: Vec<String>,                         // fields names in any struct
    names_index: HashMap<String, usize>,        // field name to it's position in the Vec
    types: Vec<String>,                         // types names
    types_index: HashMap<String, usize>,        // type name to it's position in the Vec
    lengths: Vec<u16>,                          // length of every type, same len/order as type
    structures: Vec<Structure>,                 // every struct
    // structure_ids_index: HashMap<u16, usize>,    // struct name id -> pos in structures
    structure_names_index: HashMap<String, usize>    // struct name -> pos in structures
}

impl SDNA{
    pub fn new(header: &Header, block: FileBlock) -> Result<SDNA>{
        if str::from_utf8(&block.data[0..4]).unwrap() != "SDNA"{
            return Err(Error("Error parsing dna, found dna header != SDNA".to_string()))
        }

        if str::from_utf8(&block.data[4..8]).unwrap() != "NAME"{
            return Err(Error("Error parsing dna, found names header != NAME".to_string()))
        }
        let endianness = header.endianness().unwrap();

        // Parse names
        let begin_names = 8;
        let (names, next) = sdna_string_list_and_next_pos(&block.data[begin_names..], endianness);
        let names_index = names.iter().cloned().enumerate().map(|(i, n)| (n,i)).collect();

        // Parse types
        let next = utils::next_multiple(next + begin_names, 4);
        if str::from_utf8(&block.data[next..next+4]).unwrap() != "TYPE"{
            return Err(Error("Error parsing dna, found type header != TYPE".to_string()))
        }
        let begin_types = next + 4;
        let (types, next) = sdna_string_list_and_next_pos(&block.data[begin_types..], endianness);
        let types_index = types.iter().cloned().enumerate().map(|(i,t)| (t,i)).collect();

        // Parse lengths
        let next = utils::next_multiple(next + begin_types, 4);
        if str::from_utf8(&block.data[next..next+4]).unwrap() != "TLEN"{
            return Err(Error("Error parsing dna, found tlen header != TLEN".to_string()))
        }
        let begin_lengths = next + 4;
        let lengths = sdna_u16_list_with_size(&block.data[begin_lengths..], types.len(), endianness);

        // Parse structures
        let next = utils::next_multiple(begin_lengths + 2*types.len(), 4);
        if str::from_utf8(&block.data[next..next+4]).unwrap() != "STRC"{
            return Err(Error("Error parsing dna, found structures header != STRC".to_string()))
        }
        let begin_structures = next + 4;
        let mut dna = SDNA{
            block: block,
            endianness: endianness,
            pointer_bytes: header.pointer_bytes().unwrap(),
            names: names,
            names_index: names_index,
            types: types,
            types_index: types_index,
            lengths: lengths,
            structures: Vec::new(),
            structure_names_index: HashMap::default(),
            // structure_ids_index: HashMap::default(),
        };
        dna.fill_structures(begin_structures);

        Ok(dna)
    }

    fn fill_structures(&mut self, pos_structures: usize){
        let data = &self.block.data[pos_structures..];
        let num_elements = utils::read_i32(data, self.endianness) as usize;
        let mut pos = 0;

        self.structures = (0..num_elements).filter_map(|e|{
            let structure = Structure::new(&data[pos..], self);
            pos += 4 + structure.fields().len() * 4;
            if e > 0{
                Some(structure)
            }else{
                None
            }
        }).collect();

        // let (structure_names_index, structure_ids_index) = self.structures.iter().enumerate().map(|(i,s)|{
        //     ((s.name().to_owned(), i), (s.type_idx(), i))
        // }).unzip();
        // self.structure_names_index = structure_names_index;
        // self.structure_ids_index = structure_ids_index;


        self.structure_names_index = self.structures.iter().enumerate().map(|(i,s)|{
            (s.name().to_owned(), i)
        }).collect();
    }

    pub fn size_of_type_idx(&self, type_idx: u16) -> u16{
        self.lengths[type_idx as usize]
    }

    pub fn size_of(&self, type_name: &str) -> Option<u16>{
        self.lengths.get(*self.names_index.get(type_name)?).cloned()
    }

    pub fn type_name(&self, type_idx: u16) -> &str{
        &self.types[type_idx as usize]
    }

    pub fn name(&self, name_idx: u16) -> &str{
        &self.names[name_idx as usize]
    }

    pub fn name_idx(&self, name: &str) -> Option<u16>{
        self.names_index.get(name).map(|idx| *idx as u16)
    }

    pub fn type_idx(&self, name: &str) -> Option<u16>{
        self.types_index.get(name).map(|idx| *idx as u16)
    }

    pub fn structure_idx(&self, name: &str) -> Option<i32>{
        self.structure_names_index.get(name).map(|idx| *idx as i32)
    }

    // pub fn structure_by_type_idx(&self, type_idx: u16) -> Result<&Structure>{
    //     match self.structure_ids_index.get(&type_idx){
    //         Some(idx) => Ok(&self.structures[*idx]),
    //         None => Err(Error(format!("Couldn't find structure for type id {}", type_idx)))
    //     }

    // }

    pub fn structure(&self, name: &str) -> Result<&Structure>{
        match self.structure_names_index.get(name){
            Some(idx) => Ok(&self.structures[*idx]),
            None => Err(Error(format!("Couldn't find structure named {}", name)))
        }
    }

    pub fn structures(&self) -> &[Structure]{
        &self.structures
    }

    pub fn field_structure(&self, field: &Field) -> Result<&Structure>{
        self.structure(field.type_name())
    }

    pub fn endianness(&self) -> Endianness{
        self.endianness
    }

    pub fn pointer_size(&self) -> usize{
        if self.pointer_bytes == 8{
            64
        }else{
            32
        }
    }

    pub fn pointer_bytes(&self) -> usize{
        self.pointer_bytes
    }

    pub fn parse_ptr(&self, ptr_data: &[u8]) -> Result<u64>{
        if ptr_data.len() < self.pointer_bytes(){
            Err(Error(format!("Tried to parse pointer of size {} from data of size {}", self.pointer_bytes(), ptr_data.len())))
        }else{
            let addr = if self.pointer_size() == 32{
                utils::read_u32(ptr_data, self.endianness()) as u64
            }else{
                utils::read_u64(ptr_data, self.endianness())
            };
            if addr == 0{
                Err(Error("nullptr".to_string()))
            }else{
                Ok(addr)
            }
        }
    }
}